The 12 century Cathedral of Llandaff was built on the site of an earlier church traditionally attributed to Saint Telio, the successor of Saint Dubricius who had established a 6th century community here at a ford over the River Taff. Telio was succeeded by Saint Oudoceus (also known as Euddogwy) (Died 700AD).
Specific Location: Cardiff
This site has been used for military installations since 55AD when the first Roman fort was built upon it during the pacification of the Silures Tribe.
A worm type of dragon was supposed to live at the bottom of a whirlpool in the River Taff. It was said to drown people and suck down their bodies to eat.
The above was taken from an article by Richard Freeman.